This web site provides information on the process EPA, the states, and the tribes follow to designate areas as "attainment" (meeting) or "nonattainment" (not meeting) the ground-level ozone standards established in 1997.

A designation is the term EPA uses to describe the air quality in a given area for any of six common air pollutants known as criteria pollutants. One of these pollutants is ground-level ozone. (The other criteria pollutants are particulate matter, nitrogen dioxide, carbon monoxide, sulfur dioxide, and lead.) Breathing air containing ozone can reduce lung function and increase respiratory symptoms, thereby aggravating asthma or other respiratory conditions. Ozone exposure also has been associated with increased susceptibility to respiratory infections, medication use by asthmatics, doctor visits, and emergency department visits and hospital admissions for individuals with respiratory disease. Ozone exposure may also contribute to premature death, especially in people with heart and lung disease. High ozone levels can also harm sensitive vegetation and ecosystems.